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154               PRACTICAL ORGANIC CHEMISTRY

PREPARATION 57.
m-Dinitrobenzene.   Q>H4M"

Deville,  Ann.   Chim.  Phys.,   1841   (3),  3,   187;   Hofmann,
Muspratt, AnnaJcn^ 1846, 57, 214.

30 grms. nitrobenzene.

35          (24 c.c.) fuming nitric acid ; sp. gr. 1*5.

35          (20 c.c.) cone, sulphuric acid.

The acids are mixed in a flask (500 c.c.), and the nitrobenzene
added in portions of 5  10 c.c. at a time. Heat is evolved, and
the mass becomes somewhat deeper in colour. When the nitro-
benzene has been added, the flask is heated for a short time on
the water-bath. A few drops are then poured into a test-tube of
water. The dinitrobenzene should, if the reaction is complete,
separate out as a hard pale yellow cake. If it is semi-
solid, the heating must be continued. The contents of the flask
are then. poured, whilst warm, into a large quantity of water.
The dinitrobenzene, which separates out, is filtered at the pump
and well washed with water. It is then dried. The yield is
nearly theoretical. A few grams should be recrystallisecl from
spirit. The remainder may be used for the next preparation
without further purification.

*        CCH3.NO2 + HNO3 = C0H4(NO2)2+H2O
Properties.  Colourless  long needles ; m. p. 90"' ; b. p. 297,
See Appendix i p. 279.

PREPARATION   58.
m-Nitraniline.   CG

Hofmann, Muspratt, Annalen, 1846, 57, 217.
25 grms. 7;/-dinitrobenzene.
75          (95 c.c.) spirit.
12          (13 c.c.) cone, ammonia.
The powdered dinitrobenzene, spirit and ammonia, are mixed
together in a flask (-| litre) and weighed.    Hydrogen sulphide,